The use of bleaching catalysts for stain removal has been developed over recent years. The recent discovery that some catalysts are capable of bleaching effectively in the absence of an added peroxyl source has recently become the focus of some interest, for example: WO9965905; WO0012667; WO0012808; and, WO0029537.
The search for new classes of compounds that are suitable as air bleaching catalyst is ongoing.
Various [3.3.1] bicyclo compounds and complexes thereof are discussed in the literature, see for example: Comba P. et al., J. Chem. Soc. Dalton Trans, 1998, (23) 3997-4001; Börzel et al. Chem. Eur. J. 1999, 5, No. 6, 1716 to 1721 and review by P. Comba in Coordination Chemistry Reviews 2000, 200-202, 217 to 245, entitled “Coordination compounds in the Entactic State”. These compounds are discussed in terms of their physical properties.
WO0060045, to Proctor and Gamble, discloses a bleaching system comprising: a) from about 1 ppb, by weight of a transition metal catalyst comprising: i) a transition metal; ii) a ligand having formula (I):
wherein each R is independently hydrogen, hydroxyl, C1-C4 alkyl, and mixtures thereof; R1 is C1-C4 alkyl, C6-C10 aryl, and mixtures thereof; R2 is C1-C4 alkyl, C6-C10 aryl, and mixtures thereof; R3 and R4 are each independently hydrogen, C1-C8 alkyl, C1-C8 hydroxyalkyl, —(CH2)xCO2R5 wherein R5 is C1-C4 alkyl, x is from 0 to 4, and mixtures thereof; X is carbonyl, —C(R6)2- wherein each R6 is independently hydrogen,hydroxyl, C1-C4 alkyl, and mixtures thereof; b) optionally a source of hydrogen peroxide; and c) the balance carriers and adjunct ingredients. However, the teaching of WO0060045 limits substituents at the nitrogens (3 and 7 positions) of bicyclostructure to homoaromatic carbon groups, namely alkyl and aryl.
WO0248310, to Unilever, in contrast to WO0060045 discloses compounds having a similar core structure but with the requirement that at least one of R1 and R2 is a group containing a heteroatom capable of coordinating to a transition metal.